1. Technical Field
The present invention relates to an assembly/transport apparatus including a carrier on which a transport object is mounted. More particularly, the present invention relates to an assembly/transport apparatus including a transport track for conveying a carrier on which a transport object is mounted and a return track for returning an empty carrier from which a transport object has been removed.
2. Description of the Background Art
Assembly/transport apparatuses including carriers on which transport objects are mounted are known. An assembly/transport apparatus includes a transport track and a return track. The transport track conveys a carrier on which a transport object is mounted. The transport track has one or more stop positions arranged from upstream toward downstream in the transport direction, for example. At each stop position, a carrier on which a transport object is mounted stops such that specific work can be done on the transport object. When the work is finished, the transport object is removed from the carrier. The empty carrier after the removal of the transport object is returned by the return track to the starting end of the transport track.
An assembly/transport apparatus including a transport track and return track that are disposed on the ceiling of a building is known. If a transport track and a return track are to be disposed on the ceiling of a building, the transport track and return track are arranged in a horizontal direction. Arranging a transport track and a return track in a horizontal direction requires a large space in a horizontal direction. Further, arranging the transport track and return track requires that the ceiling of the building be reinforced.
JP 2013-237521 A discloses an assembly/transport apparatus having a transport track and return track overlying each other in the top/bottom direction. The transport track and return track are supported by a frame standing on the floor. The carrier is conveyed by a screw. The screw extends along the transport track. The entire screw is composed of a plurality of screw units coupled to each other in a direction of the transport track. A driving unit that drives the screw is positioned at one end of the screw.
In the assembly/transport apparatus described in JP 2013-237521 A, the transport track and return track are positioned to overlie each other in the top/bottom direction to reduce the horizontal space required by the assembly/transport apparatus.
Further, as the transport track and return track are supported by a frame, the assembly/transport apparatus may be installed to be independent from the building, eliminating the need to reinforce the ceiling of the building.
However, the screw used in the conventional assembly/transport apparatus discussed above does not transmit driving forces very efficiently, because the angle of elevation of the screw disperses the driving force from the driving unit in directions that are different from the transport direction. The driving force dispersed by the screw has a twisting effect on the frame supporting the screw and driving unit.
Further, in the conventional assembly/transport apparatus discussed above, the entire screw is composed of a plurality of screw units. The driving unit that rotates the screw is positioned at an end of the screw. As a single driving unit rotates the entire screw, the unit is required to be a high-output one. As such, the driving force dispersed by the screw is also large, resulting in a large twisting effect on the frame.
Furthermore, in the conventional assembly/transport apparatus discussed above, a longer transport track requires a screw with a full length that is increased accordingly, which requires a driving unit with higher output. Moreover, a frame with higher rigidity must be used to counter the increased twisting effect.
Thus, the conventional assembly/transport apparatus requires a frame with a high rigidity. This results in a frame with a complicated structure and increased weight, making it difficult to install the assembly/transport apparatus.
The present application discloses an assembly/transport apparatus that has a frame with a simple structure and reduced weight and thus is easier to install.